Anal appendages: Male
odonates possess one (in dragonflies, in which
animals also possess an epiproct) or two (in
damselflies) pairs of appendages at the base of the abdomen, which are used
as claspers for holding the female during copulation. The shape of
the upper and/or lower appendages may be an important
diagnostic feature in some species.

Anal triangle: In many dragonflies,
triangular section of the hindwing base, consisting of two or more cells.
The number of cells is a guide to identification in some species.

Casque: A structure protruding from the top
of the head, frequently bearing a loose resemblance to a helmet (as in
chameleons and some birds). Casques take a variety of forms and are found on
many vertebrates; including cassowaries, many lizards and a number of frogs.
Casques are also characteristic of many hadrosaurs, a lineage of
plant-eating bipedal dinosaurs, where they exhibit perhaps their most varied
and extreme shapes.

Canthus rostralis: In reptiles and
amphibians, the line connecting the tip of the snout with the top of the eye
orbit, generally present as a ridge. The shape of the canthus rostralis is
often a useful guide to identifications. In chameleons, the canthus is often
strongly angled and distinct from the rest of the head, where it is known as
a rostral crest.

Caudal lamellae: Three leaf-like
structures protruding from the abdomen of damselfly larvae; these provide the primary means of respiration and may also be involved in defence. The
shape, relative lengths and patterning of caudal lamellae are important
features in species identification. The singular form is lamella.

Choanae: One of the defining features of
terrestrial vertebrates, choanae are the openings in the roof of the skull
that form one end of the nasal passages, the other being the nostrils.

Cloaca: In non-mammalian vertebrates, a
single opening at the underside of the body near the tail base (in reptiles,
fish, tailed amphibians and birds) or the urostyle (in
frogs). The cloaca is involved in both reproduction and waste excretion. The
cloaca is often referred to simply as the vent.

Crest (in
chameleons): The head shape of chameleons is often a valuable guide to
identification, and the presence
and form of several types of crest is used to distinguish many species; most
also have crests of spines or enlarged scales along the back, and sometimes
the belly. This can make chameleon taxonomy seem complex and daunting at
first. Terminology important in identification includes:

Dorsal crest: The crest
down the centre of the back, which may continue along the tail. Often
composed of spine-like triangular scales.

Gular crest: A row of
small spines running down the centre of the throat.

Lateral crest: A ridge
extending from behind the eye to the base of the casque on each side of the
head; where both a lateral and rostral crest is present, they form a single
continuous crest. Occasionally

this entire ridge may be referred
to as the lateral crest.

Parietal crest: The
central ridge down the front of the casque. Not always
present.

Rostral crest: A ridge of
enlarged scales along the canthus rostralis.
When a lateral crest is present,

this is a continuation of the
rostral crest. Rostral crests are normally present; whether or not they meet
at

the snout tip is important in
identification of some species.

Ventral crest: A row of
small spined or conical scales running down the centre of the belly. When
present, the ventral crest may or may not be continuous with the gular
crest.

Cuticle:
Any external protective layer in an organism, including among other examples
wax layers of plant leaves, layers of dead skin above living tissue, or
perhaps most commonly the external skeletons of
arthropods.

Dermal fringe:A fringe or flap of
skin running along part of the body. Examples include fringes running along
the limbs of some frogs, or the extensible fringes or flaps of skin between
the limbs in some gliding reptiles

Head of Furcifer
oustaleti. This species has a distinct parietal crest (centre of
casque), rostral crests that reach the snout tip but do not touch, and
lateral crests connecting the side of the head and the casque.

Dorsolateral: Relating to both the
upper (dorsal) surface of an animal and sides. The
term is often used to describe anatomical features that occur at the border
of the dorsum and flanks, though can also refer to features, such as
patterns, that extend across both the upper body and sides.

Dorsolateral folds: A
diagnostic feature in many frogs, particularly
members of the family Ranidae (typical or "true" frogs). These frogs
typically have paired dorsolateral folds, one at either side of the back,
which are visible as raised ridges of skin that run down part or all of the
length of the back.

Epiproct:
Spine-like plate projecting from the final abdominal segment in
dragonflies. The shape is an aid to larval
identification. In males, a projection beaneath the base of the epiproct
mayu also be useful in distinguishing species.

Fin (in
fish): The fins of fish are defined by their position on the body; the
shape, size and structure of different fins is often useful as an aid to
identification. Most fins are present in all fish, but some groups have lost
particular fins as they have evolved.

Anal fin: A fin on the
underside of the body, behind the vent.

Caudal fin: The tail fin;
the shape of this fin is an important feature in distinguishing many groups
of fish.

Dorsal fin: Usually a
single fin, although up to three may be present, found in both bony and
cartilaginous fish, that rises from the animal's
back. The most famous dorsal fins are of course the triangular fins of
sharks. A dorsal fin is present in most fish; however, it is lost or reduced
in rays.

Pectoral fins: A pair of
fins extending from the side of the body, one on each side, just behind the
head. The 'wings' of rays are enlarged pectoral fins.

Frons: The upper section of a dragonfly's
face, immediately in front of the eyes, which often sports dark patterning.
When used to distinguish between species, the frons generally refers to the
shape and size of this pattern.

Hemipenes: Male lizards and snakes possess
dual penises, which they use alternately when mating. When not engaged in
mating activity, the hemipenes are contained within the body, creating a
distinct hemipenal bulge at the base of the tail which can be used to
sex animals.

Interpleural
stripe: A black, line close to the centre of the
thorax when viewed in profile, a common feature of many damselflies The
interpleural lies between two prominent sutures, the humeral (upper,
below any antehumeral stripe) and
metapleural (lower). The stripe extends from close to the wing
base.

Labium (also labial mask or mask): Toothed
feeding apparatus in dragonfly and damselfly larvae, held against the front
of the head as a 'mask' when not in use, covering the mouthparts. The halves
of the mask are the labial palps, each edged with a row of teeth. The labium
can be projected forwards to capture prey on the teeth or prehensile hairs.

Lamellae: Enlarged scales on the underside of
the toe in some lizards, principally geckos. Gaps between the lamellae act
as hooks that perform the function of climbing aids.

Maxillary teeth: In vertebrates, the
teeth of the upper jaw. Whether or not maxillary teeth are present can be an
important factor in classifying frogs.

Metatarsal tubercle: An
important diagnostic feature in many frogs,
consisting of a typically hardened protrusion from base or heel of the
hindfoot. The presence or absence of a metatarsal tubercle, its shape and
size, and occasionally the number of turbercles (most frogs have at most
one) can all be useful in identifying species. Burrowing species such as
spadefoot toads often have enlarged metatarsal tubercles adapted for
digging, which may be referred to as the spade.

Mangrove frog (Fejervarya cancrivora) with a pale
mid-dorsal line.

Mid-dorsal: Centred on the upper side (dorsal
surface), such as a line or other marking that extends down the middle of
the back.

Mid-ventral: Centred on the underside (ventral
surface), such as a line or other marking that extends down the middle of
the belly.

Nuchal: Relating to the neck (for instance,
the nuchal crest in some lizards extends along the neck).

Nuptial pads: Thickened, often
hardened, pads on the fingers of many adult male frogs, with which they
clasp females while breeding. Nuptial pads may be present year-round, in
which case they are frequently smaller and less conspicuous outside the
breeding season, or may develop only during the breeding season. Males of
some species, especially those that don't engage in
amplexus, lack nuptial pads altogether.

Parotid (or parotoid) gland:
A
diagnostic feature of the frog family Bufonidae (true toads), consisting
of a round or roughly oval gland at the back of the head, behind the eye;
parotid glands are always paired, one either side of the head. The size and
shape of this gland may be a guide to species identity. The function of the
gland is to secrete a latex-like toxin to deter predators, and which can be
lethal if ingested.

Plastron: The lower half of the carapace in
turtles, consisting of a number of bony plates.

Prothorax:
The frontal segment of an insect's thorax. The
upper surface is generally protected by an armoured section, the pronotum,
which is important diagnostically feature in some
groups. In beetles, the pronotum is expanded to protect the entire thorax.

Pruinosity/Pruinescence:
A light, powdery or waxy coating over the surface of part of an
organism. Most commonly, pruinosity is associated with plants, but is also
found in some animals. The abdomens and, on occasion, other features of many
dragonflies are pruinose, for example; in this case the powdery
covering is typically a light blue or grey in colour.

Pterostigma:
Typically dark cell on the leading
edge of each wing in some insects, most conspicuously in dragonflies and
damselflies. In some groups, this may
be absent, or it may be less distinct and divided by crossveins (a
pseudopterostigma). The pterostigma acts to stabilise the tip of the
wing in flight.

Rostral: Relating to the snout (rostrum).
Often used to describe features towards the front of the head in relation to
the snout. Many lizards and a small number of frogs and snakes possess
rostral appendages, often shaped as a spike and so sometimes called
rostral spikes or horns. in this context, 'rostral' refers to features
projecting from or ahead of the snout itself.

Scale (in reptiles): Body covering composed
of keratin arranged as numerous adjoining plates. The shape, arrangement and
number of scales is an important taxonomic feature in distinguishing reptile
species and higher-level groupings. Scales are named according to their
location on the body; scales which are important in identification include:Labial scales: The scales immediately above (supralabials)and below (infralabials) the mouth, i.e.
bordering the lips. Labial scales are often larger or more elongated than
surrounding scales, and form a recognisably discrete row above and another
below the mouth. Loreal scale: A scale that separates the scale behind the nostril
from the preocular, the scale immediately in front of the eye. Absent
in some groups of snakes, and the presence or absence of a loreal scale is
thus a useful taxonomic feature.Mid-body scale rows: Counted at the widest point of a snake's or lizard's body,
the number of mid-body scales or scale rows is the number of scales on the
flanks and upper body combined (i.e. all but the ventral scales) in
cross-section.Parietal scales: Large, paired scales at the base of the head, behind
the scales surrounding the eye. The two parietals surround a smaller scale
called the interparietal. In some lizards, notably skinks, an
important taxonomic feature is whether the parietal scales are whole or
fragmented (broken into several smaller scales), and whether the two
parietals are in contact with one another behind the interparietal or are
wholly separated from each other by it.

Preocular: The scales
bordering the front of the eye, above the upper labials. Postocular
scales border the rear of the eye orbit.Subcaudals: Literally "beneath the tail". Subcaudals are the small
ventral scales of the tail, which typically occur either as a row of single
scales or in paired rows (in which case the scales are said to be divided).
Whether or not the subcaudals are divided is a diagnostic feature in some
snakes.Supraciliary scales: Row of small scales between the scales bordering
the top of the eye (supraocular) and the scales at the top of the
head.Ventral scales: Those on the animal's belly. In snakes, these
typically form a longitudinal row of large, single scales and the number of
ventrals is often an important diagnostic character. Tubercle: Descriptive term for an enlarged, rounded or spined scale,
which may be found on any part of the body, often giving a pebbly or prickly
texture to the skin.

Setae: Superficially hair-like structures
along body segments in arthropods; when especially
dense, these can give the animal a furry appearance. The distribution of
setae on different parts of the body is often important in classification.

Spiracle: A body opening in
certain animal groups which is involved in respiration, by allowing air or
water to pass into or out of the body. In larval amphibians, these are exits
for water taken up during respiration. Tadpoles possess one or two spiracles, and the number and position
of these on the body is diagnostic. Conversely, in
elasmobranchs and some primitive bony fish, a
spiracle behind each eye serves the reverse function, allowing water to
enter the body and oxygenate the gills while the animal itself is
motionless.

Stridulation: Sound produced by rubbing
two body parts, such as wing cases, spines or hairs, together. The most
familiar example is sound production by grasshoppers

Supraocular cone: In several
species of Malagasy leaf chameleons (genus Brookesia), these are the
forward-facing, broadly triangular structures jutting out from above the eye
socket. Supraocular cones are absent in a number of leaf chameleons, and so
provide a useful aid to identification.

Supratympanic fold: A glandular
structure in frogs that curves around and above the
tympanum; where the supratympanic fold is thick and fleshy, the tympanum
itself may be partially or completely concealed.

Thorax: In insects and crustaceans, the
central section of the body. The thorax is the point of attachment of the
animal's limbs and (if present) wings, and the site of vital organs such as
the heart.

Toe discs: Enlarged disc-shaped
swellings at the base of the toes and fingers in many groups of frogs. The
presence and size of toe discs is a good guide to a species' behaviour, as
enlarged toe discs are generally an adaptation for a climbing lifestyle.

Tympanum: The ear opening in
reptiles and amphibians (in amphibians, normally covered by a circular
membrane). Snakes and some lizards lack a tympanum.

Underwings:
The underside of a butterfly's wings, as seen when the animal is at rest
with wings closed. Not to be confused with the hindwings, the second
(rear) pair.

Upperwings: The top side of a
butterfly's wings as seen when the animal is at rest with wings open;
typically (but not always) the most colourfully-patterned face of the wings.
Not to be confused with the forewings, the front pair of wings.

Ventral: The underside of a bilaterally
symmetrical animal; the belly.

Vocal sac:The calling apparatus in most
male frogs, consisting of a pouch beneath the chin or, less commonly, two
pouches either to the sides of or beneath the chin, which can be inflated
with air from the lungs.

Vomerine teeth: In frogs, a small row of
teeth located in the roof of the mouth. Whether vomerine teeth are present
and where they are located is a character used in species classification.

Wing sheaths: In
exopterogyte insects, the wings develop as externally visible buds
or sheaths in larval instars;
these grow in relative size as the animal develops, before becoming
fully-functional wings in adults.

Aestivation: A state of
environmentally-induced dormancy in many animals, in which animals enter
dormancy in response to high temperatures, low humidity and, frequently,
lack of prey. Animals may aestivate for prolonged periods, a state similar
to hibernation, or only briefly to survive warm spells.

Tandem: The mating position adopted by most
dragonflies, in which the male clasps the female around the head and
thorax with his anal
appendages, so that the two are joined in flight with the male leading
the female. Once in tandem, copulation takes place in the wheel
position, in which the female's tail curls round to make contact with the
male genitalia at the base of the abdomen.

Biome: On a global scale, a biome refers to
all biological systems of a specific type; a biome may represent a division
as coarse as 'rainforest' or 'tundra', but in conservation is generally used
to describe systems with particular climates, vegetation, fauna and
characteristics found nowhere else, usually defined at continental scales or
below, such as Bornean peat-swamp forest or the Argentinean pampas. Tthe
terms 'biome' and 'ecosystem' are sometimes used interchangeably, although
in biogeography the term 'ecosystem' is more often confined to smaller-scale
biological systems; an ecosystem in this context can be thought of as being
representative of a particular biome.

Disjunct: Describing the
distribution of a species which is not continuous throughout its range, but
where two or more centres of distribution exist which are separated by areas
where the species is absent. Some species naturally occur in this pattern,
often due to historical changes in climate or geography in intervening
areas, but more usually disjunct distributions are a consequence of recent
human-induced extinctions in part of a species' range, are due to poor
knowledge of species occurrence, or arise from inadequate taxonomy when two
or more species are erroneously included within a single named form.

Endemic: Used to describe a species that
only occurs in a particular region; most often used at the scale of
countries, islands or smaller geographical features to describe species
confined to relatively small areas, but the term may also be used to
describe species that are restricted to particular habitats; a species
might, for instance, be endemic to rainforest, but may occur in rainforests
covering a comparatively large area. Endemic species are often of particular
conservation concern as, while they may often be common where they occur,
their dependence on small areas or particular types of habitat makes them
vulnerable to the effects of human activities.

Eurasia: The world's largest continental plate, consisting of the
traditional 'continents' Asia and Europe.

Gondwana:
The southern portion of the former supercontinent Pangaea, following its
break-up in the early Mesozoic (200-180 Mya). For much of this period,
Gondwana was a single landmass connecting the Southern Hemisphere
continents, with Antarctica forming the bridge between South America,
Africa, Australia and a landmass consisting of what are now India and
Madagascar. Both as the larger of the two continents that followed the
breakup of Pangaea and for its influence (through the collision of India
with Asia) on Northern Hemisphere faunas and floras, Gondwana is of
particular importance for understanding modern biogeographical patterns, as
many major groups of plants and animals evolved during the Gondwanan period.
Gondwana itself broke up throughout the Cretaceous, with India-Madagascar,
Africa, South America and finally Australia separating from Antarctica. Note
that in a biogeographical context, Gondwana only refers to the southern
continent that existed following the breakup of the supercontinent. This is
in contrast to the usage of the term in geology, in which Gondwana or
Gondwanaland also refers to a continent that preceded the creation of
Pangaea, long before multicellular life colonised the land.

Pangaea: The 'supercontinent' that existed during
the Paleozoic era, from 545 Mya to the beginning of the Triassic period 200
Mya. During this time, Pangaea was the Earth's only major landmass,
containing all the continents that exist today. This was the landmass on
which the first terrestrial life forms - invertebrates, plants and
terrestrial vertebrates - evolved and diversified, making Pangaea an
important source of biogeographical information.

Radiation: An
evolutionary term for a rapid (in evolutionary time, meaning typically
thousands to millions of years) speciation event within a single lineage. A
group of organisms may undergo a radiation if it develops a particularly
advantageous trait (as with the radiation of flowering plants), or if it is
newly introduced to a region without competitors

Amplexus: Reproductive 'embrace' used by
many frogs, in which one or occasionally more males physically grasp
females with their forelimbs while mating. Amplexus can sometimes last
for hours or even days.

Amphibian reproductive
strategies: Pond- and stream-breeding amphibians can broadly be
divided into explosive breeders,species with a short
breeding season (often no more than several days) which congregate in
large numbers around the breeding site and (in frogs) typically call in
loud choruses, and protracted breeders in which animals breed in
smaller numbers throughout the season, and may have a more extensive
aquatic phase. Most familiar frogs of disturbed areas are explosive
breeders; salamanders are typically protracted breeders.

Caudal autotomy: The ability,
common in several families of salamanders and lizards, to shed part or
all of their tails as a defensive mechanism, by severing it at a weak
point when grabbed by a predator. Nervous impulses in the severed tail
cause it to twitch for a short time, sometimes several minutes, and this
will often distract predators for long enough for the animal to escape.
The tail will subsequently regrow, but these regenerated tails
are shorter and more brittle than the original tail. In species with
unusually-shaped tails, such leaf-tailed geckos from Madagascar and
Australia, the regrown tail usually loses these features and instead
resembles a more typical lizard tail.

Dimorphism: Literally, "two forms". Used
to describe a species in which a portion of the population exhibits
consistent differences from the rest, created two distinct types within
the one species that differ in size, colouration or other attributes.
Most commonly used in the context of sexual dimorphism, in which
males may be bigger than females (or vice versa) or exhibit other
differences, but other forms of dimorphism can occur. In a number of
bird species, for example, both black and white forms may exist that
readily interbreed and belong to the same population, but in which
neither sex is consistently one colour or the other. In some cases of
sexual dimorphism, members of one sex may sometimes exhibit colouration
or other features typical of the other sex. Such individuals are termed
andromorph (where a female imitates a male) or
gynaeomorph (where a male resembles a female).

Direct development: In frogs,
direct development is the term used to describe a life cycle without a
tadpole stage. Eggs are laid, commonly in most habitats on land, and the
young grow directly into froglets within the egg, before emerging
fully-formed. Direct development has evolved in numerous lineages of
frogs and occurs in much of the world; particularly diverse
radiations are associated with the "eleutherodactyline"
frogs of South and Central America (Family Brachycephalidae and allies),
the Asian tree frog genus Philautus (family Rhacophoridae), a
lineage of true frogs in South-east Asia and New Guinea (Platymantis,
family Ranidae) and the highly diverse radiation of narrow-mouthed frogs
in New Guinea (family Microhylidae).

Ecdysis: The act of moulting in
arthropods
and related animals with a hardened exoskeleton, enabling growth which
would otherwise be inhibited by the rigid cuticle.
After separation from the body of the animal within (apolysis),
the exoskeleton breaks along weak points (points of ecdysis) allowing
the soft-bodied animal to emerge and expand before a new cuticle forms.
The discarded exoskeleton is known as an exuvium (plural
exuvia or exuviae).

Electroreception: A sense
possessed by some groups of, predominantly aquatic, animals that enables
them to hunt by homing in on the electrical activity of their prey. This
is often an adaptation for hunting in low-visibility environments.

Endopterogyte: An insect with
internal (rather than external) wing buds in
the larval stage. Larvae of endopterogyte insects often look very
dissimilar from adults, and all undergo eventual
metamorphosis during which external wings
develop. Endopterogytes include the most abundant, diverse and
evolutionarily 'advanced' insects, the most familiar being the beetles,
flies, wasps and their relatives, and moths and butterflies.

Exopterogyte: An insect in which
externally visible wing sheaths are present
during larval development, often thought of as 'primitive' insects.
Larvae characteristically resemble adult animals (although this
resemblance may be rather slight, for instance in dragonflies and
damselflies), and maturation occurs without
metamorphosis. Familiar exopterogytes include grasshoppers and their
relatives, true bugs, dragonflies and mayflies.

Hibernation: The term used to describe
a, usually fixed, period of dormancy in mammals, a response to low
external temperatures in which most metabolic processes are slowed
considerably, including respiration and maintenance of body temperature.
In 'true' (mammalian) hibernation, animals typically remain dormant in
this state for most or all of this period, without emerging to feed. The
term is used more broadly to describe any form of overwinter dormancy,
and is often applied to insects, amphibians, reptiles and other animals
as well as mammals.

Holometabolous: Description of the
life cycle of endopterogyte insects, such as beetles, flies, moths and
wasps, in which the animal undergoes
metamorphosis from a larval stage into a distinct, and often winged,
adult form. The alternative life cycle, in which no metamorphosis takes
place, is known as hemimetabolous.

Masting: A life history strategy used by
many trees, in which seeds are produced in large numbers at irregular
multiyear intervals. During a masting event, all members of the species
in the woodland or patch will set seed simultaneously, overwhelming the
ability of seed predators to consume the entire harvest. Masting is most
associated with tropical forest trees, especially in the Asian
rainforest family Dipterocarpaceae, but also occurs in temperate regions
such as European beechwoods.

Melanism: The condition caused by an
excess of the pigment melanin, resulting in an animal whose skin, hair
or feathers are entirely black.

Metamorphosis: In the life cycle of
many animals the transition from one form to another, typically from a
larval form to an adult. This type of metamorphosis is particularly
familiar from amphibians and many insects, though occurs in other animal
groups including crustaceans, fish and molluscs. The products of
metamorphosis have different names depending on the organisms; for
example, newly-metamorphosed frogs are known as froglets or
metamorphs, while newly-emerged dragonflies may be described as
teneral.

Ovoviviparity: A reproductive system in
which eggs develop fully within the mother's body, with the young inside
feeding off the yolk sac until shortly before birth. The eggs hatch inside
the mother, and live young are born shortly afterwards. This distinguishes
ovoviviparity from true viviparity (live-bearing),
in which developing animals obtain some or all of their nutrition directly
from maternal tissues.

Paedomorphism: The situation in some species with complex life
cycles, notably the axolotl, whereby the animal grows and reaches
maturity in its larval form, without undergoing metamorphosis. In some cases
it is possible to induce metamorphosis by altering environmental conditions;
this may be a natural response, or as in the axolotl may only occur in
captivity. Partial paedomorphis, in which some juvenile characteristics are
retained into adulthood, is known as neoteny.

Parthenogenesis: A state in populations of many sexual organisms in
which females are able to reproduce asexually, laying fertile eggs in the
absence of males. In some cases, parthenogenesis may require ovulation to be
stimulated by another female engaging in courtship behaviour; in others a
single female may produce young without any contact with other animals.
Offspring are necessarily clones, and are themselves invariably female.
Parthenogenesis may be facultative, in which females are able to
reproduce clonally in the absence of males, but will produce offspring
sexually when males are available. However, some parthenogenic species
altogether lack males; in others, especially species introduced to areas
outside their native range, only certain populations lack males. Many
effective colonisers, including several species of tropical gecko and the
blind snake Rhamphotyphlops braminus, exhibit parthenogenesis.

Pupa:
In holometabolous insects, the final stage
before sexual maturity. The larval form moults into a sessile pupa, often
nondescript in colour and attached to vegetation, within which the animal's
tissues are reorganised in the process of
metamorphosis.

Teneral: The soft-bodied stage between
ecdysis and the hardening of a new exoskeleton in
arthropods and their relatives. This is the
period during which an animal grows as fluid expands its tissues.
In some animals, such as odonates, changes in
colouration and aspects of physical appearance such as the development
of wings or enlarged eyes, also take place during this period.. In
dragonflies, the term is usually used to refer only to the period
immediately after the adult form emerges from the final larval
instar.

Thermoregulation: The act of
maintaining body temperature at a level that allows for continued activity.
Mammals, birds and some other organisms possess the ability to maintain
their internal temperature at a constant level using energy from the
breakdown of food. Most animals rely instead on regulating their body
temperature behaviourally, for instance by basking in sunlight and
retreating to the shade in warm periods.

Univoltine: Describing a species that
produces only one brood of offspring in a year; species with multiple broods
may be described as bivoltine, trivoltine etc. Most often used
to describe insects, such as butterflies. Conversely, animals that exhibit
slower rates of voltinism may be described as semi- (taking
two years to complete development) or partivoltine (longer periods).

Viviparity: Often known as 'live-bearing',
truly viviparous species are those in which mothers both give birth
to live young, and provide nourishment for offspring as they develop in the
mother's womb. This form of reproduction is known from most
mammals, and occurs to a lesser extent in a number of other animal groups,
including some sharks and insects.

Anthropogenic: Literally 'human-created'.
When used to describe habitats, the term refers to environments that are
predominantly man-made, and typically associated with regular human presence
- examples include urban areas, parks and gardens, and agricultural land.
More broadly, anthropogenic disturbance can refer to any form of
habitat modification with a human cause, such as selectively logged forest
or secondary regrowth following land clearance.

Ecosystem: An ecosystem is the product of all
interactions between animal and plant species and inorganic components of
their environment, such as nutrients. Ecosystems can be defined on a range
of spatial scales. A full description of an ecosystem includes not only the
characteristics of the habitat and the species which inhabit it, but also
the processes involved in transferring nutrients and energy through the
system (ecosystem processes).

Ecosystem engineer: A species whose
behaviour alters their environment in such a way that the occurrence,
abundance and/or relationships between other species are indirectly affected
(i.e., not simply reducing the abundance of a prey species). The best-known
ecosystem engineers are beavers, whose dams create ponds that provide
habitat for a range of aquatic species.

Eutrophic: A system is eutrophic if it is
'overloaded' with nutrients, a condition that, in aquatic environments, can
promote the growth of algae which block sunlight and limit the diffusion of
oxygen into the water column. On land eutrophication (typically in
the form of nitrogen deposition) can promote the spread of 'weed' species at
the expense of other plants. Eutrophic habitats can occur naturally, but are
most often considered in the context of agricultural and industrial
pollution, especially the runoff of nitrogen and phosphorous into
freshwater. Eutrophic habitats are hostile to many organisms.

Interspecific: Relating to individuals
between species, such as in the context of biological interactions (e.g.
interspecific competition is competition between species)

Intraspecific: Relating to individuals
within a species, often in the context of interactions between members of a
single species (e.g. intraspecific competition) or physical differences
between members of a species (intraspecific variation). Contrasts with
interspecific.

Microhabitat: Within a broad habitat type
(such as a forest), microhabitat defines particular elements of that
habitat's structure and climate upon which species depend, such as favoured
perch types (tree, rock, leaf litter etc.), moisture regimes, breeding or
foraging sites.

Nutrient: The generic name for any inorganic
materials that are required for the functioning of biological processes.
Nutrients may be required in either large (macronutrients) or small (micronutrients)
quantities, and most are ultimately produced by the breakdown of rocks
through weathering and chemical erosion. The most important nutrients for
plant growth, and hence for sustaining ecosystems,
are nitrogen and phosphorous.

Nutrient cycling: A fundamental
ecosystem process that describes the transfer of
nutrients through soil, plants and other organisms.
Nutrients are removed from the soil by plant roots, and are ultimately
released back into the soil by the decomposition of plant and animal
material. In many nutrient-starved ecosystems (those that receive few
nutrients from outside the system, and/or that have thin soils that provide
few nutrients of their own), such as tropical rainforest, nutrient cycling
provides most or all of the nutrients that sustain the ecosystem.

Pelagic: The open-water environment, in either
the sea or freshwater. The description of a species as pelagic indicates
that it spends the majority of its time away from shore. Colloquially large
marine creatures with a pelagic lifestyle, such as marine turtles and many
sharks, are often referred to by divers simply as pelagics.

Primary (habitat): The term used to describe
areas of the landscape with little or no apparent sign of disturbance or
human activity. In the specific case of primary forest, the term
refers more specifically to areas dominated by large, slow-growing old-growth
trees, in contrast to areas of recent regrowth where trees are typically
faster-growing and with a more open canopy.

Succession: A process of gradual habitat
evolution and replacement over time, classically from an area of bare ground
to a woodland through a process of rock weathering, soil development and
establishment by progressively longer-lived, larger plant species. In
practice, succession is a more dynamic process, with interactions between
species (such as browsers preventing tree establishment) and natural
disturbance preventing many ecosystems from reaching any 'final'
successional state. Succession can be a useful way of understanding
colonisation and competitive processes in both plants and animals, with
early pioneer species characterised by rapid dispersal, tolerance of
poor environmental conditions and fast growth rates followed by
slower-colonising species that prefer less extreme, well-vegetated habitats
and that may outcompete the pioneers in time.

Amniote: A tetrapod
characterised by the possession of an amniotic egg in the
primitive condition. This egg consists of a yolk
sac, a central cavity surrounding the embryo filled with amniotic fluid,a moist albumin (protective membrane) and a watertight shell.
Paralleling the evolution of seeds in plants and hard egg cases in insects,
the development of the amniotic egg was the vertebrates' most critical
adaptation to a fully-terrestrial lifestyle. Living amniotes include the
reptiles, mammals and birds, but not the amphibians.

Anura: The major living
order within the Amphibia in Linnean
taxonomy, containing all tail-less amphibians (i.e. frogs and toads). In a
biological sense, the term anuran is synonymous with 'frog' (a term
which also encompasses all animals commonly known as 'toads'), but is often
preferred to avoid confusion with the common usage of 'frog' (i.e. excluding
toads).

Arthropod: Literally, 'jointed-foot'. Treated
as a phylum in Linnean taxonomy, this
enormous grouping contains all animals with exoskeletons and jointed limbs,
including the major lineages Hexapoda (insects and six-legged
relatives), Crustacea and Arachnida (spiders, mites, scorpions, horseshoe
crabs and relatives). Centipedes and millipedes (the Myriapoda) are also
arthropods, and genetic evidence places the velvet worms (Onychophora) at
the evolutionary base of this group.

Binomial nomenclature: The system
of giving organisms scientific names according to
Linnean taxonomy. Each binomial consists of a specific name for a
species, in lower case, and the name of the genus of related species to
which it belongs, which always begins with a capital letter, with each
species receiving a unique combination of the two. In formal taxonomic use,
the full binomial is followed by the name of the author of the paper or book
in which the organism was first described (the authority) and the
date of its publication. This is often omitted in non-taxonomic studies. For
example, the full name of the Asian common bush frog is Polypedates
leucomystax Gravenhorst, 1829, usually referred to as Polypedates
leucomystax (the genus name can be abbreviated to its first letter after
the first use in a document, so P. leucomystax will often be seen
relating to this species). The origin of species and genus names is often a
classical European language, principally Latin or Greek, but Latinised forms
of place names, cultural groups or people, or words in non-European
languages are also frequently used.

Cladistics: The modern application of
taxonomy to identify evolutionary relationships. Cladistic taxonomy traces the evolution of specific characters (traits), and aims to define
groups of related species (clades) based on the extent to which these
features diverge from those of ancestral forms. In practice, major clades
are generally assigned to existing levels in
Linnaean taxonomy; for example a single family of frogs may represent a
clade. However, cladistics is able to identify many more levels of
evolutionary divergence than traditional taxonomy allows, and has the
ultimate goal of defining all organisms as
monophyletic groups.

Cryptic species: As used in taxonomy, a
cryptic species is one that resembles another so closely that both have
traditionally been considered a single species. Sometimes these species can
be distinguished by close scrutiny, and in these cases the crypsis is
an artefact of a poor state of knowledge regarding particular species; often
in these cases it is known or strongly suspected that multiple species are
involved, but one or more await formal description. Alternatively,
populations may be genuinely indistinguishable on the basis of external
characters, and the presence of additional species can only be established
using genetic analysis. Commonly, a single described species represents a
complex of multiple cryptic species, rather than simply two species.
Note that this use of 'cryptic' is different from the term's meaning in
ecology, where it refers to an animal's ability to camouflage itself to
match its surroundings.

Diagnostic: A feature that can be used to
reliably distinguish one taxon from others, most often
used to describe the important traits that identify specific species.

Diapsid: One of two major
amniote lineages that first appeared in the Carboniferous period
(360-300 million years ago), diverging from a common ancestor with the
synapsids. Diapsids are characterised by the
possession of a large opening (fenestra) at either side of the skull
although several lineages, including turtles, appear to have since lost this
trait. The surviving diapsids are reptiles and birds.

Elasmobranch: A member of the major
surviving group of cartilaginous fish, a group of vertebrates characterised
by skeletons made of dense connective tissue instead of bone. Sharks first
appear in the Devonian Period, 400 million years ago, and the group is today
represented by around 1,000 species of shark, skate and ray.

Eutherian: The largest and most widespread of
the three major groups of mammals, the eutherian or placental mammals
occur on every continent (represented by bats and rodents in Australia, and
by seals and whales in Antarctica). They are distinguished from the
egg-laying monotremes in giving birth to live
young, and from the marsupials in having an
extended development period within the womb and a more complex,
better-developed system of placental tissue.

Extant: Used in opposition to extinct;
i.e. an extant species or group of species is one with living members.

Linnaean system: The system of
biological classification pioneered by the 18th Century botanist Carl
Linnaeus. Organisms are grouped into one of six major levels - species,
genus, family, order, phylum and kingdom - representing a hierarchy of
similarity: organisms that appear identical to one another or nearly so
belong to a single species, with groups of similar species contained within
the same genus, genera within families and so on. Although increasingly
superseded by cladistics, the named levels of the
Linnaean taxonomy are still a convenient way of representing evolutionary
relationships, albeit relatively crudely. The most lasting contribution of
the Linnean system is the use of
binomial nomenclature for giving species scientific names.

Marsupial: Marsupials or metatherians are
a group of mammals that occur today in Australia, South and North America,
and are most famously represented by the Australian kangaroos. Several
hundred species of living marsupial exist, mostly in Australia and New
Guinea. Young marsupials are born at an earlier stage of development than
those of placental mammals, and are carried by the
mother once they leave the womb, either in a pouch or pockets on her skin,
or clinging to her body.

Monotreme: A small group
of mammals with the unusual habit of laying eggs rather than giving birth to
live young. Today the monotremes are represented by one species of platypus
in Australia, and several of echidna (spiny anteater) in Australia and New
Guinea, although the oldest fossil platypus are known from Argentina.

Phylogenetics: The practice of constructing family trees to
represent evolutionary relationships between organisms. The resulting
phylogenies effectively represent hypotheses about the relatedness of
different organisms, with the goal of identifying monophyletic groups,
clades which contain all organisms descended from
a given common ancestor. In practice, many phylogenies represent groups
which are either polyphyletic (including one or more unrelated
species, and therefore in which organisms are not all derived from one
common ancestor), or paraphyletic, in which all species descend from
the same common ancestor, but some species that are also descended from that
ancestor are excluded from the group. A classic example of the latter is the
class Reptilia. By convention, the definition of a reptile excludes birds,
although no taxonomic features are known to exist which reliably distinguish
birds from theropod dinosaurs, classified as reptiles. The discipline of
cladistics is an effort to resolve these issues and produce wholly
monophyletic phylogenies for all organisms.

Primitive: In an evolutionary sense, 'primitive'
refers to a character that is present in a lineage's common ancestor;
primitive characters may be lost in some, or even all, members of a lineage
over evolutionary time, or may be retained. Primitive characters are useful
for tracing evolutionary relationships; for example, possessing four limbs
is the primitive state in all tetrapods, including
snakes, whales and others with two or fewer limbs.

Prosimian: Any primate belonging to the lineage ancestral to
monkeys, collectively grouped into the suborder Strepsirrhini. Living
prosimians occur in Africa and Asia, and include lemurs (confined to
Madagascar and the Comoros), bushbabies (a large complex of species
resembling mouse lemurs, and found in much of mainland Africa) and Asian
lorises. The eight species of tarsier are also often regarded as prosimians,
though are usually placed in a suborder of their own.

Snout-vent length:
In reptiles, the most common measurement of body size, taken from the tip of
the snout to the cloacal opening (vent), taken as being the length of the
body excluding the tail. Adult amphibians are usually measured to the tip of
the final bone of the spine, known as the urostyle, and the term
snout-urostyle length (SUL) is often used; tadpoles are measured using
snout-vent length.

Synapsid: One of the two
major amniote lineages that diverged during the
Carboniferous period (360-300 million years ago), the other being the
diapsids. Synapsids are ultimately ancestral to the
mammals, which first appeared in the late Triassic.

Taxon: Any unit at a level of taxonomic
organisation, such as a species, family, class or
clade.

Tetrapod: Any
vertebrate with four limbs or four-limbed ancestors, including living
amphibians, reptiles, mammals and birds together with extinct vertebrate
groups that share a common ancestor with them. The term tetrapod broadly
corresponds with 'terrestrial vertebrate', and the two can be used
interchangeably. However, the former is more precise as it encompasses a
variety of taxa that have become adapted to a
fully-aquatic lifestyle, such as whales and the extinct plesiosaurs.